The PI3K/mTOR dual inhibitor NVP-BEZ235 reduces the growth of ovarian clear cell carcinoma.

Patients with clear cell carcinoma of the ovary (OCCC) have poor survival due to resistance to standard chemotherapy. OCCC has frequent activating mutations of the PIK3CA gene. The present study was conducted to clarify the efficacy of the inhibition of the PI3K-AKT-mTOR pathway in OCCC. We used 8 OCCC cell lines and 5 ovarian serous adenocarcinoma (OSAC) cell lines. The mutation status of the PIK3CA and KRAS genes was examined by direct sequencing. The IC50 values of NVP-BEZ235 (BEZ235) and temsirolimus were determined by WST-8 assay. Protein expression levels of PI3K-AKT-mTOR pathway molecules were examined by western blotting. Cell cycle distribution was analyzed by flow cytometry. Annexin V staining was used for detecting apoptosis. We also investigated the effects of BEZ235 on OCCC tumor growth in a nude mouse xenograft model. Four of the 8 OCCC cell lines showed a PIK3CA mutation while none of the 5 OSAC cell lines showed a mutation. The IC50 values of BEZ235 for the OCCC cell lines were lower than these values for the OSAC cell lines. The IC50 value of temsirolimus was higher than BEZ235 in the OCCC cell lines. The PIK3CA mutation was more frequently noted in OCCC than OSAC cells, but the sensitivity of these cell lines to BEZ235 or temsirolimus was not related to the mutation status. pHER3 and pAkt proteins were expressed more frequently in OCCC compared with OSAC. However, protein expression levels were distributed widely, and were not related to the sensitivity. Treatment with BEZ235 suppressed expression of pAkt, although treatment with temsirolimus did not. OCCC cells exhibited G1 phase arrest after treatment with BEZ235 and apoptosis with a higher concentration of the agent. BEZ235 significantly inhibited tumor growth in mice bearing OVISE and TU-OC-1 cell tumors. The present study indicated that the PI3K-AKT-mTOR pathway is a potential target for OCCC, and that BEZ235 warrants investigation as a therapeutic agent.

Dual inhibition of phosphatidylinositol 3'-kinase and mammalian target of rapamycin using NVP-BEZ235 as a novel therapeutic approach for mucinous adenocarcinoma of the ovary.

Ovarian mucinous adenocarcinoma (MAC) resists standard chemotherapy and is associated with poor prognosis. A more effective treatment is needed urgently. The present study assessed the possibility of molecular-targeted therapy with a novel dual inhibitor of phosphatidylinositol 3'-kinase (PI3K) and mammalian target of rapamycin (mTOR), NVP-BEZ235 (BEZ235) to treat of MAC. Seven human MAC cell lines were used in this study. The sensitivity of the cells to BEZ235, temsirolimus, and anticancer agents was determined with the WST-8 assay. Cell cycle distribution was assessed by flow cytometry, and the expression of proteins in apoptotic pathways and molecules of the PI3K/Akt/mTOR signaling pathways was determined by Western blot analysis. We also examined the effects of BEZ235 on tumor growth in nude mice xenograft models. The cell lines showed half-maximal inhibitory concentration values of BEZ235 from 13 to 328 nmol/L. Low half-maximal inhibitory concentration values to BEZ235 were observed in MCAS and OMC-1 cells; these 2 lines have an activating mutation in the PIK3CA gene. NVP-BEZ235 down-regulated the protein expression of phosphorylated (p-) Akt, p-p70S6K, and p-4E-BP1, suppressed cell cycle progression, up-regulated the expression of cleaved PARP and cleaved caspase 9, and increased apoptotic cells. Synergistic effects were observed on more than 5 cell lines when BEZ235 was combined with paclitaxel or cisplatin. The treatment of mice bearing OMC-1 or RMUG-S with BEZ235 significantly suppressed tumor growth in MAC xenograft models without severe weight loss. We conclude that the PI3K/Akt/mTOR pathway is a potential therapeutic target and that BEZ235 should be explored as a therapeutic agent for MAC.

Checkpoint kinase inhibitor AZD7762 overcomes cisplatin resistance in clear cell carcinoma of the ovary.

OBJECTIVE: Checkpoint kinase (Chk) inhibitors are thought to increase the cytotoxic effects of DNA-damaging agents and are undergoing clinical trials. The present study was aimed to assess the potential to use the Chk1 and Chk2 inhibitor, AZD7762, with other anticancer agents in chemotherapy to treat ovarian clear cell carcinoma. METHODS: Four ovarian clear cell carcinoma cell lines were used in this study. We treated the cells with AZD7762 and anticancer agents, then assessed cell viability, cell cycle distribution, apoptosis, and the expression of protein in apoptotic pathways and molecules downstream of the Chk signaling pathways. We also investigated the effects of these drug combinations on tumor growth in a nude mouse xenograft model. RESULTS: Synergistic effects from the combination of AZD7762 and cisplatin were observed in all 4 cell lines. However, we observed additive effects when AZD7762 was combined with paclitaxel on all cell lines tested. AZD7762 effectively suppressed the Chk signaling pathways activated by cisplatin, dramatically enhanced expression of phosphorylated H2A.X, cleaved caspase 9 and PARP, decreased the proportion of cells in the gap 0/ gap 1 phase and the synthesis-phase fraction, and increased apoptotic cells. Combinations of small interfering RNA against Chk 1 and small interfering RNA against Chk2 enhanced the cytotoxic effect of cisplatin in both RMG-I and KK cells. Finally, treating mice-bearing RMG-I with AZD7762 and cisplatin significantly suppressed growth of tumors in a xenograft model. CONCLUSIONS: The present study indicates that chemotherapy with AZD7762 and cisplatin should be explored as a treatment modality for women with ovarian clear cell carcinoma.

Outcome of stage IB2-IIB patients with bulky uterine cervical cancer who underwent neoadjuvant chemotherapy followed by radical hysterectomy.

BACKGROUND: We performed a retrospective study to clarify the outcome of stage IB2-IIB patients with bulky cervical cancer who underwent neoadjuvant chemotherapy (NAC) followed by radical hysterectomy and adjuvant treatment. METHODS: Sixty-five patients with bulky stage IB2-IIB cervical cancer, treated at Tottori University Hospital between 2001 and 2011, were examined retrospectively. The indication for adjuvant treatment was limited to the following pathological high-risk factors: pelvic lymph node (PLN) involvement, parametrial infiltration (PI), and a compromised surgical margin. RESULTS: Fifty-one patients had squamous cell carcinoma (SCC) and 14 non-SCC. Three patients were ineligible for radical hysterectomy after NAC, and underwent concurrent chemoradiotherapy. In 62 patients who underwent radical hysterectomy, 13 had only PLN involvement and 6 only PI, and 10 had both PLN involvement and PI. In 33 patients who had no adjuvant treatment, 6 recurred, and only one underwent salvage chemotherapy. In 29 patients who underwent adjuvant treatment, 15 recurred and 11 died. Multivariate Cox proportional analysis revealed that PLN involvement was an independent prognostic factor. CONCLUSIONS: Even if the indication for adjuvant treatment is limited to only high-risk patients, about 70 % of stage IB2-IIB patients with bulky cervical cancer could be cured by NAC followed by radical hysterectomy. Additionally, about 40 % of those patients could be cured without adjuvant treatment. In contrast, the strategy for patients with PLN involvement, who account for about 35 % of stage IB2-IIB bulky cervical cancer after NAC, should be carefully reconsidered based on quality of life and cost-effectiveness.

Establishment and characterization of a novel ovarian clear cell adenocarcinoma cell line, TU-OC-1, with a mutation in the PIK3CA gene.

A new cell line of human ovarian clear cell adenocarcinoma (CCC), TU-OC-1, was established and characterized. The cells showed a polygonal-shaped morphology and grew in monolayers without contact inhibition and were arranged like a jigsaw puzzle. The chromosome numbers ranged from 64 to 90. A low rate of proliferation was observed, similar to other CCC cell lines tested (OVTOKO, RMG-I, and OVAS), and the doubling time was 38.4 h. The respective IC50 values of cisplatin and paclitaxel were 12.2 µM and 58.3 nM. Mutational analysis revealed that TU-OC-1 cells harbored a PIK3CA mutation at codon 542 (E542K) in exon 9, which is a mutation hot spot on this gene. We observed that phosphorylated Akt protein was overexpressed in TU-OC-1 cells by western blot analysis. Heterotransplantation to nude mice produced tumors that reflected the original. This cell line may be useful to study the chemoresistant mechanisms of CCC and contribute to novel treatment strategies.

Activation of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway overcomes cisplatin resistance in ovarian carcinoma cells.

OBJECTIVE: This study was aimed to elucidate the roles of the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3'-kinase (PI3K)/Akt pathways in regulating cytotoxicity induced by cisplatin (CDDP) in ovarian carcinoma cells. METHODS: We treated 7 ovarian cancer cell lines with CDDP alone or with CDDP and either a PI3K inhibitor (LY294002), a MEK inhibitor (PD98059), or a MEK/ERK activator (phorbol 12-myristate 13-acetate [PMA]) and assessed cell viability, expression of MEK/ERK and PI3K/Akt, cell cycle distribution, and apoptosis. We also investigated the effect of combination treatment on survival in a xenograft model. RESULTS: The cell lines showed half-maximal inhibitory concentrations (IC50) of CDDP from 2.4 to 26.9 µmol/L. KFr, a CDDP-resistant cell line developed from KF cells, showed an IC50 of CDDP of 9.6 µmol/L. Five of the cell lines with IC50 values of 9.6 µmol/L or greater were defined as CDDP-resistant. Cisplatin and LY294002 had an additive effect on inhibiting cell growth, and CDDP and PD98059 had and antagonistic effect on cell growth in all cell lines. In CDDP-resistant cells, CDDP and PMA dramatically suppressed the cell growth, up-regulated the expression of phosphorylated ERK and cleaved caspase-9, down-regulated the expression of checkpoint kinases, and increased the proportion of cells in the synthesis-phase fraction and apoptotic cells. The treatment of nude mice with CDDP and PMA prolonged survival in an ovarian cancer xenograft model. CONCLUSIONS: The present study indicates that further study is warranted to determine the effectiveness of combination treatment with CDDP and PMA for platinum-resistant ovarian carcinoma.

Establishment and characterization of a novel ovarian serous adenocarcinoma cell line, TU-OS-4, that overexpresses EGFR and HER2.

A new line of human ovarian serous adenocarcinoma cells, TU-OS-4, was established and characterized. The cells showed a short, spindle-shaped morphology and grew in monolayers without contact inhibition while forming an arrangement resembling a jigsaw puzzle. Chromosome numbers ranged from 55 to 73. The proliferation rate was lower than other serous adenocarcinoma cell lines tested (KF, SHIN-3, and SK-OV-3), and the doubling time was 53.3 h. Western blot analysis showed that TU-OS-4 cells overexpressed epidermal growth factor receptor, human epidermal growth factor receptor (HER) 2, and phosphorylated HER2 protein. The IC(50) values to cisplatin, paclitaxel, and lapatinib were 25.8 µM, 686 nM, and 183 nM, respectively. Heterotransplantation in nude mice reflected the original tumor of the cells. These results suggested that this cell line would be useful to study chemoresistant mechanisms and contribute to establishing novel treatment strategies for patients with ovarian cancer.

Inhibiting the mTOR pathway synergistically enhances cytotoxicity in ovarian cancer cells induced by etoposide through upregulation of c-Jun.

PURPOSE: The mTOR pathway is thought to be a central regulator of proliferation and survival of cells. Rapamycin and its analogs are undergoing clinical trials in patients with epithelial ovarian cancer. This study aimed to assess the potential to use rapamycin and anticancer agents in combination for first- and second-line chemotherapy to treat ovarian cancer. EXPERIMENTAL DESIGN: We used six ovarian serous adenocarcinoma cell lines (KF, KOC-2S, SHIN-3, SK-OV-3, TU-OS-3, and TU-OS-4) in this study. We treated the cells with rapamycin and anticancer agents, then assessed cell viability, apoptosis, and the expression of protein in apoptotic pathways and molecules downstream of the mTOR signaling pathways. We also investigated the effect of these drug combinations on survival in nude mouse xenograft models. RESULTS: Synergistic effects were observed in five cell lines from the combination of etoposide and rapamycin. However, we observed antagonistic effects when rapamycin was combined with gemcitabine, cisplatin, or paclitaxel on more than two cell lines. Rapamycin dramatically enhanced apoptosis induced by etoposide and the expression of cleaved caspase 9. This effect was associated with upregulation of phosphorylated c-Jun and downregulation of Bcl-xL. The synergistic interaction of rapamycin and etoposide was lower when the c-Jun pathway was suppressed by a c-Jun N-terminal kinase inhibitor (SP600125). Finally, treating nude mice with rapamycin and etoposide significantly prolonged survival in the model mice with ovarian cancer xenografts. CONCLUSIONS: Chemotherapy with rapamycin and etoposide combined is worth exploring as a treatment modality for women with epithelial ovarian cancer.

Preoperative and intraoperative assessments of depth of myometrial invasion in endometrial cancer.

OBJECTIVE: Preoperative and intraoperative assessments of myometrial invasion (MI) are commonly used for planning surgical procedures such as dissection of the para-aortic node; however, the assessments often differ from the final diagnosis determined by pathological examination. The present study evaluated the accuracy of preoperative and intraoperative assessments of MI. METHODS: A total of 191 patients with endometrial cancer, who underwent hysterectomy from 1995 to 2007 in Tottori University Hospital, were included in this study. One hundred seventy-four patients underwent endometrial curettage or Pipelle biopsy preoperatively. Histological grade was compared between preoperation and postoperation. Magnetic resonance imaging (MRI) was performed before surgery, and the depth of MI was assessed as 3 levels (no MI, <50%, and >50%). During surgery, the uterine wall was incised at the most invasive part, and then, intraoperative gross assessment was evaluated as less than or greater than 50%. RESULTS: Histological evaluation revealed that 34 patients had no invasion, 97 had less than 50% MI, and 60 had greater than 50% MI. On MRI assessment, 135 patients had correct diagnoses, and the accuracy was 70.7%. Regarding the diagnosis of greater than 50% MI depth, the accuracy, the sensitivity, and the specificity of the MRI assessment were 83.2%, 75.0%, and 85.7%, respectively. Seventeen patients were overestimated, and 15 patients were underestimated by the MRI assessment. On intraoperative gross assessment, 162 patients had correct diagnoses, 8 patients were overestimated, and the remaining 21 patients were underestimated. The accuracy of the gross assessment was 84.8%, the sensitivity was 65.0%, and the specificity was 93.9%. The preoperative grading accuracy was 71.8% (125/174). A discrepancy between preoperative and postoperative grades was more frequent in a low-grade tumor. The incidence of underdiagnosis was significantly higher in patients with a grade 3 (G3) tumor than in those with a G1 or G2 tumor in both assessments. CONCLUSIONS: The present study suggests that gross assessment may be useful to determine MI of less than 50%, although patients with a G3 tumor were more frequently underestimated.

Combination chemotherapy of oxaliplatin and 5-fluorouracil may be an effective regimen for mucinous adenocarcinoma of the ovary: a potential treatment strategy.

Resistance of ovarian mucinous adenocarcinoma to standard chemotherapy with paclitaxel and carboplatin is associated with poor prognosis, and an effective treatment is needed. The present study aimed to identify an effective chemotherapy for ovarian mucinous adenocarcinoma. Five human ovarian mucinous adenocarcinoma cell lines (MN-1, OMC-1, RMUG-L, RMUG-S, TU-OM-1) were used in this study. Sensitivity of the cells to the anticancer agents was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and we assessed drug sensitivity by calculating the assay area under the curve for each agent. Protein expression was confirmed by Western blot analysis. We also examined the efficacy of combination chemotherapy on survival in a xenograft model of nude mice. The IC(50) to anticancer agents ranged widely. The assay area under the curve indicated that two of five cell lines (MN-1, TU-OM-1) were sensitive to oxaliplatin, 5-fluorouracil and etoposide, and only one (TU-OM-1) was sensitive to 7-ethyl-10-hydroxycamptothecin, which is an active metabolite of camptothecin. All cell lines were resistant to cisplatin and paclitaxel. The combination of oxaliplatin and 5-fluorouracil resulted in additive or synergistic effects on all cell lines. The combination of oxaliplatin and 5-fluorouracil significantly prolonged survival in a ovarian mucinous adenocarcinoma xenograft model of nude mice. Protein expression levels of the excision repair cross-complementation group 1 were lower in oxaliplatin sensitive cell lines. Exposure to 5-fluorouracil down-regulated cross-complementation group 1 expression in ovarian mucinous adenocarcinoma cells. We conclude that combination chemotherapy consisting of oxaliplatin and 5-fluorouracil was an effective treatment for ovarian mucinous adenocarcinoma and may be a pivotal candidate for a novel treatment strategy.

PTEN is involved in the signal transduction pathway of contact inhibition in endometrial cells.

PTEN is involved in the regulation of normal cellular functions in addition to its well-known role as a tumor suppressor. In the present study, we have shown that stable transfection of the PTEN gene into PTEN-mutated endometrial carcinoma cells leads to contact inhibition accompanied by a decreased level of phosphorylated-Akt (p-Akt) expression, an increase in p27(Kip1), and a decrease in beta-catenin. PTEN-induced cells with contact inhibition exhibit G0-G1 cell-cycle arrest, and the Ki-67 labeling index is reduced. These changes are canceled by transfection of a double-stranded short-interfering RNA against the PTEN gene. Normal endometrial stromal cells increase their PTEN expression when reaching confluence; this is followed by changes in the expression of Akt-related proteins in the same way as in tumor cells. These results indicate that PTEN, p-Akt, p27, and beta-catenin are involved in the signal transduction of contact inhibition and suggest that PTEN may, in part, control the proliferation of endometrial carcinoma cells through the induction of contact inhibition.

PTEN-positive and phosphorylated-Akt-negative expression is a predictor of survival for patients with advanced endometrial carcinoma.

PTEN and the PI3K/Akt pathway are involved in the development and/or progression of endometrial carcinoma. To clarify the impact of the pathway-related molecules on prognosis, we analyzed PTEN, phosphorylated-Akt (p-Akt), and Ki-67 expression by immunohistochemistry in 99 patients with advanced endometrial carcinoma. PTEN-negative or PTEN-mixed staining was found in 66% of tumors. Positive staining of p-Akt was found in 40% of tumors. Loss of PTEN expression (negative or mixed) was significantly associated with positive p-Akt expression. The patients with PTEN-positive and p-Akt-negative expression clearly showed a higher survival rate than patients in the other groups. Subsequent multivariate analysis revealed that the combination of PTEN/Akt expression was an independent prognostic factor. Examining the relationship between p-Akt expression and Ki-67 labeling index (LI), we found that negative p-Akt was related to a decrease in Ki-67 LI. Additionally, the patients with low Ki-67 LI, as determined by p-Akt-expression status, had a better prognosis. In the present study, we demonstrated that PTEN-positive and p-Akt-negative expression was a predictor of survival for patients with advanced endometrial carcinoma. This study suggests the clinical significance of PTEN and p-Akt expression analysis in treatment decisions for patients with advanced endometrial carcinoma.

Expression of the c-myc gene as a predictor of chemotherapy response and a prognostic factor in patients with ovarian cancer.

The present study was conducted to determine whether and how expression of the c-myc gene is related to the response to chemotherapy in patients with epithelial ovarian cancer. This study includes 101 consecutive patients with stage Ic to IV epithelial ovarian cancer who underwent primary surgery followed by platinum-based chemotherapy. Immunohistochemical studies were performed to detect Ki-67 and ARF proteins. Apoptotic cells were identified by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling method. Mutation of the p53 gene was screened by polymerase chain reaction (PCR)-single strand conformation polymorphism analysis and confirmed by direct sequencing. mRNA expression of c-myc was determined by means of reverse transcription-PCR. Apoptotic index (AI) and ARF labeling index (LI) were significantly increased and Ki-67 LI was decreased after chemotherapy in patients from whom specimens could be obtained before and after chemotherapy. AI, ARF LI, and Ki-67 LI were not related to p53 gene status. A significant correlation between expression of c-myc and ARF LI was observed. Of 38 patients with measurable lesion, 23 (60.5%) responded to chemotherapy and 15 (39.5%) did not. Tumors with the wild-type p53 gene responded significantly better to chemotherapy than did tumors with the mutation. Responders showed a higher expression of c-myc than nonresponders (468 +/- 76 vs. 187 +/- 68). The receiver operating characteristic (ROC) curve according to chemoresponse demonstrated that the cut-off value of c-myc expression was 200. Patients with c-myc expression of more than 200 had a better 5-year survival rate (69.8% vs. 43.5%; 101 patients). Multivariate analysis revealed that c-myc expression was an independent prognostic factor. Our results suggest that the expression of c-myc gene is related to chemoresponse and might be a useful prognostic factor in patients with epithelial ovarian cancer.

Activity of docetaxel in paclitaxel-resistant ovarian cancer cells.

PURPOSE: The aim of this study was to determine the behavior of docetaxel (DTX) in ovarian cancer cells resistant to paclitaxel (PTX). METHODS: We used human ovarian adenocarcinoma cell lines KF, KFTx (PTX-resistant KF), SK-OV-3, and HAC-2. The sensitivity of the cells to PTX or DTX was determined by the MTT assay. Cellular accumulation of PTX and DTX was measured by high-performance liquid chromatography. mRNA of MDR-1 was detected by RT-PCR. Cell cycle distribution was determined by flow cytometry after exposure to the IC(50) of each drug. Bcl-2 phosphorylation was determined by Western blot analysis. Activity for tubulin polymerization of each drug was examined by a beta-tubulin polymerization assay. RESULTS: KFTx cells had a 5.5-fold greater resistance to PTX and a 7.3-fold greater resistance to DTX than KF cells, indicating that KFTx cells had acquired cross-resistance to DTX. SK-OV-3 cells were sensitive and HAC-2 cells were resistant to both PTX and DTX. The gene expression of MDR-1 increased after exposure to DTX in KF and KFTx cells. Residual cellular accumulation of PTX and DTX was significantly lower in KFTx cells than in KF cells. In contrast, MDR-1 expression was not detected in SK-OV-3 and HAC-2 cells. Flow cytometric analysis indicated no differences in alterations of cell cycle distribution following exposure to the two drugs. Bcl-2 phosphorylation occurred after exposure to DTX at a concentration equivalent to the clinical dose, but did not occur after exposure to PTX in KFTx cells. In HAC-2 cells, Bcl-2 phosphorylation was not detected after exposure to DTX or PTX at concentrations equivalent to the clinical doses. DTX showed greater tubulin polymerization activity than PTX in KFTx cells. beta-tubulin polymerization did not correlate with the concentration of PTX or DTX, suggesting that alteration in the tubulin reaction might contribute to the resistance in HAC-2 cells. CONCLUSIONS: The present study suggests that the mechanisms involved in cytotoxicity of and resistance to PTX and DTX do not differ, but DTX has a greater cytotoxic potential in PTX-resistant cells with an efflux system.

Leptomycin B enhances CDDP-sensitivity via nuclear accumulation of p53 protein in HPV-positive cells.

Cervical cancer, which commonly contains a wild-type p53 gene, is highly correlated with human papilloma virus (HPV) infection. Because the oncoprotein E6, derived from HPV, inhibits the function of p53 protein, the inhibition of apoptosis via the p53 pathway by HPV may be related to cisplatin (CDDP)-sensitivity in cervical cancer. We conducted the present study to determine whether and how HPV is related to CDDP-sensitivity in HPV-positive cervical cancer cells. We used cervical carcinoma cell lines HeLa with integrated HPV 18 and SiHa with integrated HPV 16. An HPV-negative cell line, Yumoto, with wild-type p53 gene was used as a control. Leptomycin B (LMB) enhanced sensitivity to CDDP and CDDP-induced apoptosis in HeLa and SiHa cells, but not in Yumoto cells. After exposure to LMB or CDDP alone, we observed weak p53 staining in HeLa, SiHa and Yumoto cells. Nuclear p53 staining was significantly increased by combined treatment with CDDP and LMB in HeLa and SiHa cells, but not in Yumoto cells. The expression of p53 and Bax protein increased with exposure to CDDP and was enhanced by LMB in HeLa and SiHa cells. The present study demonstrated that LMB enhanced CDDP-sensitivity via nuclear accumulation of p53 protein in HPV-positive cells.